Heat oil in medium skillet on medium-high heat. Cook beef 4-5 minutes, while breaking up large pieces until cooked through. Add onions, garlic and ginger. Cook 3-4 minutes, stirring occasionally, until onions are softened. Stir in mirin and 1 tablespoon Broth Concentrate; mix gently until well combined.
Meanwhile, cook noodles as directed on package. Rinse under running water; drain well. Divide noodles between two individual serving bowls.
Combine hot water and remaining Broth Concentrate; pour evenly over noodles. Top with warm beef mixture, radishes and green onions before serving.
Substitute ground pork or turkey for the beef.
Mirin is a Japanese sweet cooking wine available in the Asian section of a well-stocked grocery store.
Udon noodles are also available in the refrigerated and frozen aisle at most Asian markets.